The Research Cell Sorting and Flow Cytometry Facility offers Fox Chase Cancer Center (FCCC) investigators the capability of analyzing cells by up to 14 independent measurements, 12 of which are based on immunofluorescence and two on light scattering. This Facility is used by 36 peer-reviewed funded investigators (an increase from 21 or 71% from the previous review) across 9 Research Programs and by investigators within all three FCCC Divisions. Ninety-five percent (95%) of this usage is by peer-reviewed funded investigators. Major applications of the flow cytometer include discrimination and isolation (sorting) of cell subpopulations (at up to 20,000 cells/sec), isolation of rare variant (1/10[7]) cell lines, characterization of tumors or cell lines, and single cell cloning of cell lines by direct deposition into 96-well plates. In addition to providing many more fluorescence detectors (increase from 5 to 12), the recently upgraded sorter provides high-speed 4-stream sorting and digital detection. A UV-capable laser enables measurement of calcium flux and viable cell DNA content. In addition to the 3-laser 12-color cell sorter (FACS-VantageSE/DiVa), the Facility also includes an analysis-only 8-color LSR-II and a three-color FACScan. The Facility aids users with advice on experimental design (including availability of reagents and appropriate fluorochromes), sample preparation, and data interpretation. Software developed with the FCCC Bioinformatics group, the Flow-LIMS, is used for data annotation, organization, and archiving. Analysis is done on investigator's laboratory computers using a highly interactive, graphical software program, FlowJo. Hour usage (currently estimated at over 80% of theoretical capacity) has increased 65% since the last review and is projected to increase similarly over the next five years. Equitable access to the Facility is assured by a Faculty Oversight Committee.